From 74e76b725d270a7d800ba472b780eaac0d9cfc78 Mon Sep 17 00:00:00 2001 From: Luis Machado Date: Fri, 19 Jun 2020 17:37:33 -0300 Subject: AArch64: Implement the memory tagging gdbarch hooks This patch implements the memory tagging gdbarch hooks for AArch64, for the MTE feature. gdb/ChangeLog: YYYY-MM-DD Luis Machado * aarch64-linux-tdep.c: Include target.h, arch-utils.h, value.h. (aarch64_linux_get_atag, aarch64_linux_tagged_address_p) (aarch64_linux_memtag_mismatch_p, aarch64_linux_set_memtags) (aarch64_linux_get_memtag, aarch64_linux_memtag_to_string): New functions. (aarch64_linux_init_abi): Initialize MTE-related gdbarch hooks. * arch/aarch64-mte-linux.c (make_ltag_bits, make_ltag) (aarch64_linux_set_ltag, aarch64_linux_get_ltag): New functions. * arch/aarch64-mte-linux.h (MTE_LOGICAL_TAG_START_BIT) (MTE_LOGICAL_MAX_VALUE): Define. (make_ltag_bits, make_ltag, aarch64_linux_set_ltag) (aarch64_linux_get_ltag): New prototype. --- gdb/aarch64-linux-tdep.c | 209 +++++++++++++++++++++++++++++++++++++++++++ gdb/arch/aarch64-mte-linux.c | 36 ++++++++ gdb/arch/aarch64-mte-linux.h | 19 ++++ 3 files changed, 264 insertions(+) diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c index fa76d87..0cc2e74 100644 --- a/gdb/aarch64-linux-tdep.c +++ b/gdb/aarch64-linux-tdep.c @@ -30,6 +30,7 @@ #include "symtab.h" #include "tramp-frame.h" #include "trad-frame.h" +#include "target.h" #include "target/target.h" #include "regcache.h" @@ -46,6 +47,9 @@ #include "arch/aarch64-mte-linux.h" +#include "arch-utils.h" +#include "value.h" + /* Signal frame handling. +------------+ ^ @@ -1458,6 +1462,186 @@ aarch64_linux_gcc_target_options (struct gdbarch *gdbarch) return {}; } +/* Helper to get the allocation tag from a 64-bit ADDRESS. + + Return 0 for success and non-zero otherwise. */ + +static int +aarch64_linux_get_atag (CORE_ADDR address, CORE_ADDR *tag) +{ + gdb::byte_vector tags; + + /* Attempt to fetch the allocation tag. */ + if (target_fetch_memtags (address, 0, tags) != 0) + return 1; + + /* Only one tag should've been returned. Make sure we got exactly that. */ + gdb_assert (tags.size () == 1); + + /* Although our tags are 4 bits in size, they are stored in a + byte. */ + *tag = tags[0]; + + return 0; +} + +/* Implement the tagged_address_p gdbarch method. */ + +static bool +aarch64_linux_tagged_address_p (struct gdbarch *gdbarch, struct value *address) +{ + gdb_assert (address != nullptr); + + CORE_ADDR addr = value_as_address (address); + + /* Remove the top byte for the memory range check. */ + addr = address_significant (gdbarch, addr); + + /* Check if the page that contains ADDRESS is mapped with PROT_MTE. */ + if (!linux_address_in_memtag_page (addr)) + return false; + + /* We have a valid tag in the top byte of the 64-bit address. */ + return true; +} + +/* Implement the memtag_mismatch_p gdbarch method. */ + +static bool +aarch64_linux_memtag_mismatch_p (struct gdbarch *gdbarch, + struct value *address) +{ + gdb_assert (address != nullptr); + + /* Make sure we are dealing with a tagged address to begin with. */ + if (!aarch64_linux_tagged_address_p (gdbarch, address)) + return false; + + CORE_ADDR addr = value_as_address (address); + + /* Fetch the allocation tag for ADDRESS. */ + CORE_ADDR atag = 0; + + if (aarch64_linux_get_atag (addr, &atag) != 0) + return false; + + /* Fetch the logical tag for ADDRESS. */ + gdb_byte ltag = aarch64_linux_get_ltag (addr); + + /* Are the tags the same? */ + if (ltag == atag) + return false; + + return true; +} + +/* Implement the set_memtags gdbarch method. */ + +static int +aarch64_linux_set_memtags (struct gdbarch *gdbarch, struct value *address, + size_t length, const gdb::byte_vector &tags, + enum memtag_type tag_type) +{ + gdb_assert (address != nullptr); + + CORE_ADDR addr = value_as_address (address); + + /* Set the logical tag or the allocation tag. */ + if (tag_type == tag_logical) + { + /* When setting logical tags, we don't care about the length, since + we are only setting a single logical tag. */ + addr = aarch64_linux_set_ltag (addr, tags[0]); + + /* Update the value's content with the tag. */ + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); + gdb_byte *srcbuf = value_contents_raw (address); + store_unsigned_integer (srcbuf, sizeof (addr), byte_order, addr); + } + else + { + /* Make sure we are dealing with a tagged address to begin with. */ + if (!aarch64_linux_tagged_address_p (gdbarch, address)) + return 1; + + /* With G being the number of tag granules and N the number of tags + passed in, we can have the following cases: + + 1 - G == N: Store all the N tags to memory. + + 2 - G < N : Warn about having more tags than granules, but write G + tags. + + 3 - G > N : This is a "fill tags" operation. We should use the tags + as a pattern to fill the granules repeatedly until we have + written G tags to memory. + */ + + size_t g = get_tag_granules (addr, length, MTE_GRANULE_SIZE); + size_t n = tags.size (); + + if (g < n) + { + warning (_("Got more tags than memory granules. Tags will be " + "truncated.")); + } + else if (g > n) + warning (_("Using tag pattern to fill memory range.")); + + if (target_store_memtags (addr, length, tags) != 0) + return 1; + } + return 0; +} + +/* Implement the get_memtag gdbarch method. */ + +static struct value * +aarch64_linux_get_memtag (struct gdbarch *gdbarch, struct value *address, + enum memtag_type tag_type) +{ + gdb_assert (address != nullptr); + + CORE_ADDR addr = value_as_address (address); + CORE_ADDR tag = 0; + + /* Get the logical tag or the allocation tag. */ + if (tag_type == tag_logical) + tag = aarch64_linux_get_ltag (addr); + else + { + /* Make sure we are dealing with a tagged address to begin with. */ + if (!aarch64_linux_tagged_address_p (gdbarch, address)) + return nullptr; + + if (aarch64_linux_get_atag (addr, &tag) != 0) + return nullptr; + } + + /* Convert the tag to a value. */ + return value_from_ulongest (builtin_type (gdbarch)->builtin_unsigned_int, + tag); +} + +/* Implement the memtag_to_string gdbarch method. */ + +static std::string +aarch64_linux_memtag_to_string (struct gdbarch *gdbarch, + struct value *address, + enum memtag_type tag_type) +{ + gdb_assert (address != nullptr); + + struct value *v_tag = aarch64_linux_get_memtag (gdbarch, address, tag_type); + + if (v_tag == nullptr && tag_allocation) + error (_("Error getting tag from target")); + + CORE_ADDR tag = value_as_address (v_tag); + + return string_printf ("0x%s", phex_nz (tag, sizeof (tag))); +} + static void aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) { @@ -1515,6 +1699,31 @@ aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) data associated with the address. */ set_gdbarch_significant_addr_bit (gdbarch, 56); + /* MTE-specific settings and hooks. */ + if (tdep->has_mte ()) + { + /* Register a hook for checking if an address is tagged or not. */ + set_gdbarch_tagged_address_p (gdbarch, aarch64_linux_tagged_address_p); + + /* Register a hook for checking if there is a memory tag mismatch. */ + set_gdbarch_memtag_mismatch_p (gdbarch, + aarch64_linux_memtag_mismatch_p); + + /* Register a hook for setting the logical/allocation tags for + a range of addresses. */ + set_gdbarch_set_memtags (gdbarch, aarch64_linux_set_memtags); + + /* Register a hook for extracting the logical/allocation tag from an + address. */ + set_gdbarch_get_memtag (gdbarch, aarch64_linux_get_memtag); + + /* Set the allocation tag granule size to 16 bytes. */ + set_gdbarch_memtag_granule_size (gdbarch, MTE_GRANULE_SIZE); + + /* Register a hook for converting a memory tag to a string. */ + set_gdbarch_memtag_to_string (gdbarch, aarch64_linux_memtag_to_string); + } + /* Initialize the aarch64_linux_record_tdep. */ /* These values are the size of the type that will be used in a system call. They are obtained from Linux Kernel source. */ diff --git a/gdb/arch/aarch64-mte-linux.c b/gdb/arch/aarch64-mte-linux.c index ce603b0..999a51d 100644 --- a/gdb/arch/aarch64-mte-linux.c +++ b/gdb/arch/aarch64-mte-linux.c @@ -32,3 +32,39 @@ get_tag_granules (CORE_ADDR addr, size_t len, unsigned int granule_size) /* We always have at least 1 granule. */ return 1 + (e_addr - s_addr) / granule_size; } + +/* See arch/aarch64-mte-linux.h */ + +CORE_ADDR +make_ltag_bits (CORE_ADDR value) +{ + return value & MTE_LOGICAL_MAX_VALUE; +} + +/* See arch/aarch64-mte-linux.h */ + +CORE_ADDR +make_ltag (CORE_ADDR value) +{ + return make_ltag_bits (value) << MTE_LOGICAL_TAG_START_BIT; +} + +/* See arch/aarch64-mte-linux.h */ + +CORE_ADDR +aarch64_linux_set_ltag (CORE_ADDR address, CORE_ADDR tag) +{ + /* Remove the existing tag. */ + address &= ~make_ltag (MTE_LOGICAL_MAX_VALUE); + + /* Return the new tagged address. */ + return address | make_ltag (tag); +} + +/* See arch/aarch64-mte-linux.h */ + +CORE_ADDR +aarch64_linux_get_ltag (CORE_ADDR address) +{ + return make_ltag_bits (address >> MTE_LOGICAL_TAG_START_BIT); +} diff --git a/gdb/arch/aarch64-mte-linux.h b/gdb/arch/aarch64-mte-linux.h index d3f4485..4ee6de3 100644 --- a/gdb/arch/aarch64-mte-linux.h +++ b/gdb/arch/aarch64-mte-linux.h @@ -32,10 +32,29 @@ /* We have one tag per 16 bytes of memory. */ #define MTE_GRANULE_SIZE 16 +#define MTE_LOGICAL_TAG_START_BIT 56 +#define MTE_LOGICAL_MAX_VALUE 0xf /* Return the number of tag granules in the memory range [ADDR, ADDR + LEN) given GRANULE_SIZE. */ extern int get_tag_granules (CORE_ADDR addr, size_t len, unsigned int granule_size); +/* Return the 4-bit tag made from VALUE. */ +extern CORE_ADDR make_ltag_bits (CORE_ADDR value); + +/* Return the 4-bit tag that can be OR-ed to an address. */ +extern CORE_ADDR make_ltag (CORE_ADDR value); + +/* Helper to set the logical TAG for a 64-bit ADDRESS. + + It is always possible to set the logical tag. */ +extern CORE_ADDR aarch64_linux_set_ltag (CORE_ADDR address, + CORE_ADDR tag); + +/* Helper to get the logical tag from a 64-bit ADDRESS. + + It is always possible to get the logical tag. */ +extern CORE_ADDR aarch64_linux_get_ltag (CORE_ADDR address); + #endif /* ARCH_AARCH64_LINUX_H */ -- cgit v1.1